Holder for lamp-filaments.



ZZ W L; GLASBR. HOLDER FOB LAMP FILAMBNTS APPLICATION -r n.nn run. is, 1907.

1,022,543, Patented Apr. 9, 1912.

Witnesses: Inventor:

- tory LUDWIG- GLASER, OF BERLIN, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

11 )LDER FOR LAMP-FILAMENTS.

. Specification of Letters Patent.

Patented Apr. 9, 1912..

To all who-m it may concern: I

Be it known that I, Lunwro Gnxsnn, a subject of the Grand Duke of SaXe-Coburg- Gotha, residing at Berlin, Germany, have invented certain new and useful Improve ments in Holders for Lamp-Filaments, of which the following is a specification.

Incandescent lamps with filaments containing tungsten or tungsten-oxygen com pounds are manufactured by mixing the filament material with a plastic means such as starch or gum solution and then shaping filaments of proper form therefrom. The plastic binding means is then removed and the filaments, rendered brittle by this treat-- ment, are attached to currentconducting wn'cs.

Since a long filament path is necessary for the ordinary potentials of 110 or 220 volts, the individual filament loops must be pro tectcd by means of suitable holders or anchors. It is necessary to make these holders from non-conductors since otherwise they might easily cause short circuit-s. Such holders are made, for example, in osmium lamps, by mixing thoria or thorium oxid with 10 per cent. of magnesium oXid and then pressing the mixture in well known manner into sticks which after forming and firing are inserted as permanent holders in the lamps. Such holders have proven stable at the temperatures at which osmium burns. Since, however, the temperatureof tungsten filaments is considerably higher than that of other filaments, the difficulty is encountered that the filament readily becomes fused to such holders or adheres thereto particularly with direct current; if the lamp is cut out of circuit the firmly adhering-filament is broken by reason of the contraction caused by cooling.

The drawing accompanying this specification shows one method of. using refracholders in a lamp.' The filament path includes the three loops 1, 2 and 3 supported andconnccted by the leading-in conductors 4.- and 5 and theconducting wires 6 an 7. Each of these filaments or loops is held in place by a refractory holder- 8 loosely engaging with one leg of the filament and held rigidly in place in any suitable manner as by a glass pedestal 9 fused to the globe of the lamp w shape in the usual u brought-to a temperature of at least 2000 G.

As I have discovered, it is necessary to raise the fusing point of the holders. Holders of pure th'orium oXid or of magnesium oxid have proved best.

According to my present invention holders are formed of pure thorium oxid; but as holders made from ordinary thorium oXid are very brittle and have no real stability, the method of manufacture may advantageously be as follows :Garefully prepared thorium oXid of extreme fineness of grain is employed and the holders are pressed into way. Thev are then in a suitable furnace, such for instance as that shown in United States Patent to Arsem, No. 785,535, March.21,-1905. The

holders exhibit a brilliant luster on the surface after firing, the luster being apparently due to vaporized material in the furnace used for producing incandescence. This material formed on the surface of the thorium oxid holder is a glaze like compound. Such glazing is best removed by dipping the holder into a mixture of hydrofluoric and sulfuric acid whereby the impurity on the surface is dissolved and the pure thorium oxid remains behind. It is of course possible to proceed in the same manner with holders which are made from mixtures of oxids in order to obtain greater stability. In these likewise there is obtained a surface of pure thorium oXid which does not have the property of adhering to thefilament.

It is possible to utilize holders of other materials as a core and cover them with pure oxid- The holders may serve as can riers for the filaments in all lamps with high fusion lighting filaments.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The process of manufacturing holders for filaments, which consists in shaping the holders from refractory oXid, firing said holders to at least 2000? C. and then removing the glaze formed by the firing treat- ,ment.

2. The process of manufacturing holders for filaments, which consists in shaping the holders from'refractory oxid, firing to at least 2000 C. and dissolving from the surface everything except thorlum oxid.

'. 3. The process of finishing oxid filament Copies of this 2000" C. and thenclipping in a strong acid. mlxture Capable of removlng from the surholclers which consists in. firing to altleast face of the holder everything but thoriumoxicl.

4. A holder of refretotory oxi d for lamp filaments composed mainly of mixed oxide but having a'surface of a substantially puye oxid'; v

5. A refractory holder for lam-p filaments composed of a body of mixed refractory material having a surface of substantially pure Witnesses than the remainder of said -HA'NS Gumm 1 GUSTAV MATH-US. 1

patent 'mav be obtained for five cents each by addressing the Commissiouer of Patents,

Washingcon, D. C. 

